Liquid Measure. The system of units of volume or capacity rather than weight that is commonly used in measuring liquid products or commodities. In the U. S. the units include the fluid ounce (q.v.), the pint, quart (q.v.) and gallon (q.v.), and in the metric system (q.v.) they are the milliliter (q.v.), liter (q.v.), hectoliter (100 liters) , and kiloliter (1000 liters).